EP0282172A1
Expired / Lapsed
EP
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Control systems for heat exchangers
Assignee: INTERNATIONAL CONTROL AUTOMATION FINANCE SA
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Filing: 1988-02-15
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Granted: —
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Expires: 2008-02-15
Abstract
Abstract A temperature control system for a superheater of a drum or separator type fossil fuel fired steam generator develops a feed forward signal (F 2c ) that continuously adapts itself to changes in system variables to adjust the enthalpy (h₃) of the steam entering the superheater to change the heat absorption therein in accordance with changes in system variables to thereby maintain a substantially constant enthalpy (h₄) of the steam discharged from the superheater. The system develops (27,31) a feedback signal responsive to changes in the temperature (T₄) of the steam discharged from the superheater (1) to readjust the enthalpy (h₃) of the steam entering the superheater as required to maintain the temperature (T₄) of the steam discharged from the superheater at a predetermined set point value (29).
Inventors
- 👤 Donald Joseph Dziubakowski
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-06 10:08
CPC Classifications
F; F22; F22B; F22B35/00; F22G; F22G5/00; F22G5/12
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
102 words
A control system for a heat exchanger (1) in which heat is exchanged between two heat carriers, the control system comprising means (21) for generating a feed forward signal (F 2c ), corresponding to a calculated value ( ΔH c ) of the heat absorbed in one of the heat carriers from the other, required to maintain the enthalpy (h₄) in said one of the heat carriers leaving the heat exchanger (1) at a predetermined value, and means (8) under the control of said feed forward signal (F 2c ) for adjusting the heat absorption in said one of the heat carriers.
Claim 2
Dependent Claim
102 words
A control system for a heat exchanger (1) in which heat is exchanged between two heat carriers, the control system comprising means (21) for generating a feed forward signal (F 2c ), corresponding to a calculated value ( ΔH c ) of the heat absorbed in one of the heat carriers from the other, required to maintain the enthalpy (h₄) in said one of the heat carriers leaving the heat exchanger (1) at a predetermined value, and means (8) under the control of said feed forward signal (F 2c ) for adjusting the heat absorption in said one of the heat carriers.
Claim 3
Dependent Claim
85 words
A system according to claim 1, including means (27,31) for generating a feedback control signal corresponding to the difference between the temperature (T₄) of said one heat carrier leaving the heat exchanger (1) and a predetermined set point temperature (29), and means (23) under the control of said feedback control signal for modifying said feed forward control signal (F 2c ) as required to maintain the temperature (T₄) of said one heat carrier leaving the heat exchanger (1) at the predetermined set point value (29).
Claim 4
Dependent Claim
68 words
A system according to claim 1 or claim 2, for a heat exchanger (1) which is convection superheater heated by flue gas from a fossil fuel fired steam generator, wherein the means (8) under the control of said feed forward signal (F 2c ) comprises means for adjusting the rate of flow (F 2A ) of a coolant modifying the enthalpy of the steam entering the superheater (1).
Claim 5
Dependent Claim
78 words
A system according to claim 1 or claim 2, for a heat exchanger (1) which is a convection superheater heated by flue gas from a fossil fuel fired steam generator, wherein the means (8) under the control of said feed forward signal (F 2c ) comprises means for adjusting the rate of flow of water discharged into the steam entering the superheater (1) and thereby modifying the enthalpy and the rate of flow of steam entering the superheater.
Claim 6
Independent Claim
64 words
A system according to any one of claims 1 to 4, wherein the means (21) for generating a feed forward signal (F 2c ) comprises a function generator responsive to the rate of flow (F₄) of said one heat carrier through the heat exchanger (1) to generate an output signal ( ΔH c ) varying in non-linear relationship to said rate of flow (F₄).
Claim 7
Dependent Claim
38 words
A system according to claim 5, wherein said function generator includes means (13) operative under steady state conditions to adjust said non-linear relationship in accordance with change in the rate of heat transfer between the two heat carriers.
Claim 8
Independent Claim
69 words
A system according to any one of claims 1 to 4, for a heat exchanger (1) which is convection superheater heated by flue gas from a steam generator supplied (5,7) with fuel and air for combustion, wherein said means (21) for generating a feed forward signal (F 2c ) comprises a function generator responsive to the rate of flow of steam through and flue gas across the superheater (1).
Claim 9
Dependent Claim
43 words
A system according to claim 7, wherein the rate of flow of flue gas is determined by means responsive to the difference (F₅ - F₄) between the rate of flow (F₅) of air supplied for combustion and the rate (F₄) of steam generation.
References Cited (Backward Citations)
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